KeyEvent: update comment

Change-Id: I1ea491e7e23670bf0ea83392710010b557803178
aapt: localizations: be more aggressive

* errors instead of warnings for:
  * A localized string for which no default-locale version exist.
  * A localized translation of an translateable="false" string.

Change-Id: Ib700fe323019f285f5a1931fe96500b2de03106b